路基压实效果的分析与探讨

对土基的压实意义及影响路基压实效果的因素进行阐述,以提高路基施工质量。     

New Retrieval Method Based on Relative Entropy for Language Modeling with Different Smoothing Methods

A language model for information retrieval is built by using a query language model to generate queries and a document language model to generate documents. The documents are ranked according to the relative entropies of estimated document language models with respect to the estimated query language model. Two popular and relatively efficient smoothing methods, the Jelinek- Mercer method and the absolute discounting method, are used to smooth the document language model in estimation of the document language, A combined model composed of the feedback document language model and the collection language model is used to estimate the query model. A performacne comparison between the new retrieval method and the existing method with feedback is made, and the retrieval performances of the proposed method with the two different smoothing techniques are evaluated on three Text Retrieval Conference （TREC） data sets. Experimental results show that the method is effective and performs better than the basic language modeling approach; moreover, the method using the Jelinek-Mercer technique performs better than that using the absolute discounting technique, and the perfomance is sensitive to the smoothing peramters.     

嫩江流域道路运输存在的主要问题及其开发构想

嫩江流域是中国东北部的重要边陲重地 ,发展流域内的交通运输有其重要意义     

提高函授毕业论文质量的途径

函授毕业论文与答辩是学生学习期间最后一个综合性实践教学环节。目前函授毕业论文的质量不容乐观,主要是学生、指导教师和管理等方面存在一些问题,应加强毕业论文质量的过程控制,通过建立相应的组织机构、建立质量控制程度、选聘指导教师、完善评价标准、建立激励机制等措施,提高函授毕业论文的质量。     

公路工程涵洞防水失效原因及设计

总结归纳了公路涵洞失效的设计、选材、施工和养护的四大原因,针对涵洞容易发生渗漏的重点部位和不同的防水要求,提出各个部位的防水设计和材料的选择。     

从水质水量联合角度评价鉴江流域可用水资源量

首先介绍满足流域水功能区水质目标的可用水资源量联合评价方法。该方法通过水量平衡和污染物质的质量平衡原理,建立单元系统的水量水质模型,依据水质水量资料确定模型参数;然后利用模型推求单元系统的可用水资源量;最后推广应用到河流多区段系统。将该评价方法应用到广东鉴江流域,计算该流域的可用水资源量。结果表明,可用水资源量与水质污染现状、水功能区的水质目标、河道生态需水量等有关。     

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针对外地客流进入城市中心区域时各停车换乘备选点(P+R)合理停车泊位规模的确定问题，在分析市外客流进入城市中心区域时出行过程与机理的基础上，以所有客流出行(自城市外围到达市中心区域)总的出行费用(私人车辆行驶时间与公交行驶时间总行程时间、换乘时间、停车费用等)最小为目标，建立确定各P+R处停车泊位规模的双层规划模型，并给出模型的求解算法，最后以一个仿真实例进行了说明。     

全路危险货物运输计算机监管系统

利用跨越式发展的理念和分布式计算、网络通讯、网络安全、数据库、数据挖掘等技术设计了全路危险货物运输计算机监管系统的网络拓扑架构,构建了基于审核的危险货物运输流程管理、基于认证与授权的运输责任审核功能体系与危险货物配装与仓储布局的数学模型。应用结果表明统一的全路危险货物运输计算机监管系统为危险品的运输安全提供了保障。     

THE EDDY LOSSES OF A MAGNETIC THRUST BEARING

Accurate calculations of losses associated with the operation of magnetic bearings are particularly important for high speed applications where the rotor losses are expected to be large and for some particular applications where even low power losses will be critical. Power losses in the magnetic thrust bearing is often neglected, but if there is misaligned in the rotor and bearing, the magnetic field in the thrust bearing is no longer axisymmetric one, or the dynamic control current in the winding is time dependent one, eddy currents are caused to flow inside the conducting material, then the power losses are very important for magnetic bearing design. This paper presents an analytical model of a thrust magnetic bearing, and the magnetic fields, forces and losses of thrust magnetic bearing are calculated. In the calculations the frequency of dynamic control current is up to 1 000 Hz, rotating speed is from 60 rpm to 1 200 rpm, and the non-linearity of material is also taken into consideration. The results shows that if the magnetic field is not saturation, the eddy losses is proportional to dynamic control current frequency and a square function of dynamic control current, and also 5/2 power function of shafts speed.     

路面弯沉变化规律及检测

论述了沥青路面弯沉变化的三个阶段及分析测定弯沉的正确时间，着重介绍贝克曼梁弯沉仪测试弯沉的关键所在。